Related Experiment Videos
Chick embryo DNA polymerase alpha. Polypeptide components and their microheterogeneity
The Journal of Biological Chemistry
|April 25, 1982
Summary
Researchers purified chick embryo DNA polymerase alpha, revealing it comprises two main types of subunit polypeptides. This purification and analysis provide insights into the enzyme
Area of Science:
- Molecular Biology
- Enzymology
Background:
- DNA polymerase alpha is crucial for DNA replication.
- Understanding its subunit composition is key to deciphering its function.
Purpose of the Study:
- To purify and characterize DNA polymerase alpha from chick embryos.
- To determine the subunit composition and structural relationships of the purified enzyme.
Main Methods:
- Ammonium sulfate fractionation and column chromatography for enzyme purification.
- Nondenaturing and SDS-polyacrylamide gel electrophoresis for protein analysis.
- Two-dimensional tryptic peptide mapping for structural comparison of polypeptides.
Main Results:
- Purified DNA polymerase alpha exhibited high specific activity.
- Electrophoresis revealed two major protein components associated with polymerase activity.
- SDS-PAGE identified high molecular weight (130-155 kDa) and low molecular weight (51-59 kDa) polypeptide clusters.
- Peptide mapping indicated structural similarity within the low molecular weight polypeptides and within the high molecular weight polypeptides, suggesting minor modifications create heterogeneity.
- No significant structural homology was found between high and low molecular weight polypeptides.
Conclusions:
- Chick embryo DNA polymerase alpha is composed of two distinct types of subunit polypeptides.
- Heterogeneity within the high and low molecular weight polypeptide groups arises from minor modifications.
- The enzyme's basic structure involves two fundamentally different subunits.